1. Field of the Invention:
This invention relates to a method for generating oxygen gas using chemicals. More specifically, it relates to an improved catalyst, consisting at least in part of a cobalt salt and an organic acid or a salt thereof, for generating oxygen gas by contact with a peroxygen compound such as sodium percarbonate in water.
This invention may be used in emergency oxygen generators, medical equipment, beauty equipment and the like as an effective means for generating oxygen gas.
2. Description of the Prior Art
Until now, oxygen cylinders have been the primary source of oxygen used in evacuation from a fire, oxygen deficiency accidents during underground construction, and other situations requiring an emergency oxygen supply. However, in addition to being heavy and unwieldy, oxygen cylinders are expensive, require expert skill in handling, and carry with them a host of other complications related to actual use.
In recent years, a number of proposals have been made dealing with oxygen gas generation methods and devices that are small and lightweight, and the handling and operation of which requires no special expertise. Among these are methods that involve contacting a decomposition catalyst with a peroxygen compound such as hydrogen peroxide solution, sodium percarbonate, sodium perborate, and the like. For example, methods using such metallic compounds as Mn, Fe, Ni, Co, Cu, Pb, Cr, V, and W as catalysts (see Japanese Unexamined patent applications Nos. 54-26988, 54-26989, 54-26990, and 54-26991, for example) have been disclosed. Another type of method uses polyhydric alcohols or salts as oxygen generation regulators, in addition to the above-mentioned catalysts (e.g., Japanese Unexamined patent application 54-109091).
However, known catalyst systems such as those mentioned above are inadequate for generating a constant and continuous flow of oxygen gas. In addition, these react with sodium percarbonate or sodium perborate and the like, to form hydroxides or oxide precipitates. Furthermore, these catalysts are difficult to handle and dispose of, and are visually unappealing, making them undesirable for use in medical and beauty salon equipment. Thus, a soluble catalyst on which precipitate does not form is highly desirable.